System and method of dynamic packet transmission for AGPS

Abstract

A system and method for dynamically transferring satellite data packets through GPRS (General Packet Radio Service) in an AGPS(Assisted Global Positioning System) is disclosed. The satellite data are transmitted in dynamic size of segments so as to improve the transmission efficiency. When the network communication is stalled or broken, the segments being successfully received are not necessary to be resent. But only the failed segments are re-transmitted so that the time and bandwidth for data transmission are reduced, and the positioning process is prevented from delay by the transmission failure.

1 . A system for dynamically and efficiently transferring satellite data packets in an AGPS (Assisted Global Positioning System), comprising: 
 a Basic Station System having a plurality of stations for transferring said satellite data packets;    a server for dynamically transmitting said satellite data in dynamic size of data segments, comprising a satellite database for storing data of each satellite in a coverage range of said Basic Station System based on every time period and a central processing unit for determining dynamic size of data segments of transmission of said satellite data; and    a AGPS cellar phone for requesting and receiving said satellite data covering a current position of said cellar phone, comprising:    a communication module for transmitting a request of acquiring satellite data and receiving said satellite data , a control module for monitoring a reception status of each satellite data segment and integrating said satellite data segments after receiving all satellite data segments, and a memory module for registering said received satellite data segments.    
     
     
         2 . The system of  claim 1  wherein said central processing unit determines sizes of data segments according to transmission conditions.  
     
     
         3 . The system of  claim 1  wherein said control module integrates said satellite data segments into a packet size of GPRS(General Packet Radio Service).  
     
     
         4 . The system of  claim 1  wherein said server transmits a segment size before transmitting each satellite data segment.  
     
     
         5 . The system of  claim 4  wherein said segment size data have a size of one kilobyte.  
     
     
         6 . The system of  claim 4  wherein said server transmits an ending tag after a data segment is completely transmitted.  
     
     
         7 . The system of  claim 1  wherein said current position of said cellar phone is determined by a micro-cell surrounded by stations of said Basic Station System that transfers said request of acquiring satellite data.  
     
     
         8 . A method for transferring satellite data packets in an AGPS composed of a cellar phone, a Basic Station System and a server, comprising steps of: 
 sending a request for satellite data from said cellar phone through said Basic Station System to said server;    determining at said server a micro-cell position of said cellar phone according to stations of said Basic Station System that transfers said request for satellite data;    searching data of a plurality of satellites corresponding to said micro-cell;    transmitting data segments of said satellites in dynamic sizes;    receiving and storing said data segments at said cellar phone; and    integrating said data segments into complete satellite data after receiving all data segments.    
     
     
         9 . The method of  claim 8  wherein said server transmits a segment size data before transmitting each satellite data segment.  
     
     
         10 . The method of  claim 9  wherein said segment size data have a size of one kilobyte.  
     
     
         11 . The method of  claim 9  wherein said server transmits an ending tag after a data segment is completely transmitted.  
     
     
         12 . The method of  claim 8  wherein said satellite data segments are integrated into a packet size of GPRS.  
     
     
         13 . The method of  claim 8  wherein said cellar phone sends a request for next data segment when said data segments are not fully received.